FIG. 5 is a cross sectional view of a conventional induction heating cooker showing the concept of its structure. Cooking pot 41 as a load of heating is placed on top plate 42. Heating coil (hereinafter referred to as coil) 43 heats cooking pot 41. Infrared sensor 44 detects infrared radiation of cooking pot 41, and temperature calculator 45 calculates a temperature of cooking pot 41 based on an output from infrared sensor 44. Controller 46 controls current supply to coil 43 in accordance with an output from temperature calculator 45. In the above-configured induction heating cooker, the temperature of cooking pot 41 is detected directly by means of an infrared radiation coming from the bottom of cooking pot 41; thus it can make use of quick-responding temperature detection. The induction heating cooker of the above-described structure is disclosed in, for example, Japanese Patent Unexamined Publication No. H3-184295.
However, an induction heating cooker of the above-described structure designed to be compatible with a low resistance cooking pot made of aluminum, copper or the like material having a low magnetic permeability and a high electrical conductivity comparable to or higher than that of aluminum demonstrates a poor cooking performance. This is because it requires buoyancy reducing plate 47 made of aluminum or the like non-magnetic-metal having a high electrical conductivity to be disposed above coil 43, in order to reduce buoyancy caused during induction heating between coil 43 and pot 41.
In this case, the temperature of buoyancy reducing plate 47 sometimes goes as high as approximately 300-400° C. by self heat generation due to magnetic flux of coil 43. Accordingly, the infrared radiation from buoyancy reducing plate 47 will have an energy several tens of times that from the bottom of pot 41, whose temperature is 100-200° C. When the infrared radiation from buoyancy reducing plate 47 partly reaches to infrared sensor 44 directly or indirectly after being reflected by top plate 42, temperature calculator 45 delivers incorrect information of temperature detection to controller 46 after receiving signal from infrared sensor 44. Upon receiving the temperature information, controller 46 lowers the output to coil 43. This invites an insufficiency in the heating power, and deteriorates the cooking performance.